It is known that frequently in supermarkets devices are placed for dispensing plastic bags, having the object of helping the operators and/or the customers in inserting into said bags the items purchased at the supermarket. There are also known bag opening devices which are incorporated in the supermarket check-out counters. Devices of this kind are for example described in U.S. Pat. No. 4,085,822 and in U.K. Patent Appln. No. 2,055,084.
Moreover, there has been recently invented, and forms the object of the Italian Patent Appln. No. 22455 A/89 of the same Applicant, an integrated machine suitable to be incorporated in a supermarket check-out counter, which automatically dispenses the plastic bags one at a time from a continuous strip of bags, opens them underneath a suitable mouth located on the counter upper surface, and ejects them after they have been filled.
All the above mentioned prior art apparatus and machines comprise a device for opening the plastic bags one at a time and for keeping them open as long as they are filled by the customer and/or the check-out operator. Such known devices, though very functional and reliable, are not without inconveniences, such as jamming, tearing of the bag edges and so on.
It is therefore an object of the present invention to provide a device free from these inconveniences, for automatically opening the bags and keeping them firmly in an open position as long as they are filled.
This object is attained by a device comprising two slides capable of mutual approaching and departing motion along an horizontal rail in a symmetrical direction as compared with a central position where the plastic bag is to be opened, wherein on each slide is mounted a pair of rollers, in contact with each other, operated by a motor-reducer in such a way to simultaneously rotate the rollers of a pair in the opposite direction compared with the rollers of the other pair, said pairs of rollers being able to contact the opposite sides of a plastic bag for grasping them and then pulling them apart, and subsequently to rotate them in an inverted direction for releasing them from grip.
The bag opening device according to the present invention has the advantage of having a very simple structure and therefore the maximum reliability. Another advantage of the bag opening device according to the present invention is of economic nature, due to its simple structure which requires reduced manufacturing costs.